Vanderbilt Law Review


Jennifer Arlen

First Page



Behavioral economic analysis of law presents an important challenge to conventional law and economics, strengthened in part by the fact that conventional law and economics is itself a behavioral approach to law. Indeed, conventional law and economics can be viewed as the first widely-adopted behavioral approach to law. A central contribution of Ronald Coase's pathbreaking article was the claim that one cannot determine the effect of a law by simply looking at the law itself--at the conduct the law requires. Instead, one must determine how people will respond to the law.' Legal rules, he argued, do not dictate behavior-they simply establish prices and sanctions for various actions. Thus the initial allocation of a resource will not necessarily determine its ultimate use because people will bargain when doing so is mutually profitable. This is, at its core, a behavioral analysis of law.

Where behavioral economic analysis of law and conventional law and economics differ, however, is in the model of human behavior they employ. Conventional law and economics assumes that people exhibit rational choice: that people are self-interested utility maximizers with stable preferences and the capacity to optimally accumulate and assess information Law and economics scholars do not claim that this rational choice model perfectly captures all human behavior. But they do claim that deviations from rational choice generally are not systematic, and thus generally will cancel each other out. For example, law and economics scholars argue that even if people do not accurately estimate the risk that they will be injured, some people will overestimate the risk while others will underestimate it, producing only "noise" and not a systematic bias. These scholars thus assert that rational choice, while not a perfect description of human behavior, is the best workable approximation of human behavior.

Behavioral economic analysis of law scholars argue that people do not behave consistently with rational choice theory, and, moreover, that the deviations from rational behavior are systematic, not random. Most people are likely to exhibit certain biases, they assert, and thus these deviations from rational choice do not cancel each other out. Indeed, behavioral economic analysis of law scholars argue that biased reasoning is a more plausible model of human behavior than is rational choice because biased reasoning is what natural selection would most likely produce. These systematic deviations from rational choice theory present a challenge to conventional law and economics. Conventional law and economics generally seeks to influence-or at least describe the effects of-actual policy in the real world. Yet if people regularly behave differently than the economists' model predicts, the results of this analysis may be suspect.